Letters: Van’s bad vibrations stump dealers

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Updated: January 3, 2012 2:19PM

Q: Help! Around 70,000 miles, our 2001 full-size Dodge 2500 van developed a noticeable vibration that only occurs between 48 and 52 mph. It’s there under power and coasting. Three separate dealers have checked it from top to bottom. The U-joints have been replaced and the driveshaft has been balanced. Also, we put on new Michelin tires, but the vibration is still there.

The dealers are stumped. Do you have any ideas? – Jeff, e-mail

A: Have the dealers used a vibration analyzer? A vibration analyzer can help the technician pinpoint the source of the vibration. The vibration analyzer picks up the frequency and amplitude of the vibration and can lead the technician to either the driveline or the wheel/tires.

It’s possible that one of the wheels could have excessive lateral or radial run out. This problem can go undetected during tire removal/installation. Other than checking the wheels for excessive run out, a vibration analyzer should be used so no more unnecessary components get replaced.

Q: I own a 1997 Chevrolet Lumina. Recently the transmission stopped working properly. I believe it’s an electronic problem because I can turn the engine off and restart it, and sometimes the problem temporarily goes away. Do you know what could be causing this? – Wayne, New Lenox

A: You’re probably correct. It does seem like it could be an electrical issue. There could be a poor electrical connection at the powertrain control module connector or one of the electrical circuits between the PCM and the transmission.

It’s also possible that the pressure regulating solenoid inside the transmission could be acting up. It controls the hydraulic pressure inside the transmission and greatly affects the performance of the unit. A scan tool should be connected to your vehicle to see if there are any stored or active diagnostic trouble codes, which may help the technician pinpoint the fault. Also, the scan tool can be used to observe various data in regard to the transmission to aid in diagnosis.

Q: It’s been a while since we’ve heard anything about the recall that Toyota had regarding unintended acceleration concerns. I’m interested in purchasing a car and was wondering if the newer Toyotas are OK. What do you think? – Mike, Oak Lawn

A: Those safety concerns have been resolved and shouldn’t prevent you from considering a new Toyota vehicle.

Q: There’s a loud ticking noise coming from the engine in my 2005 Mazda3 when I first start the engine. Someone told me it might be something wrong with the variable valve timing mechanism. What do you think? – Stan, Chicago

A: It’s quite possible. Mazda issued a service bulletin (No. 01-010/11) to address this concern. The bulletin involves inspecting and possibly replacing the mechanism with revised components.

Questions for Ira Siegel? Call the Auto Advisor Hotline at (708) 633-6839 or e-mail ira.siegel.is@gmail.com. Siegel is an automotive instructor and an automotive service excellence-certified master auto technician.